Effect of phenotypic recurrent selection on genetic diversity of non-dormant multifoliolate lucerne (Medicago sativa L.) populations

The nutritional quality of lucerne (alfalfa, Medicago sativa L.) plants correlates positively with the presence of multifoliolate (MF) leaves. Using phenotypic recurrent selection, we developed populations with an increased percentage of MF expression from 6.7% in the original population (C0) to 77.7% in the fourth cycle (C4). The effect of selection on genetic diversity within and among populations was evaluated. The populations C0 and C4 were represented by 40 plants genotyped by using 25 simple sequence repeats (SSR). The number of alleles per locus was large in both C0 and C4, averaging 6.28. The within-population genetic diversity (HE) overall estimation was 0.723 for C0 and 0.726 for C4, the absence of significant difference between the two populations indicating that the genetic diversity was as large in C4 as in C0. The Nei’s population differentiation (GST) overall estimation was 0.013, meaning that only 1.3% of the total genetic diversity was between populations and 98.7% was within populations. An efficient selection process was conducted without any increase in inbreeding or genetic drift.

Genetic progress of phenotypic recurrent selection in popcorn

Popcorn is widely consumed in the south of Minas Gerais; however, up to now no specific breeding program for the region has been carried out. Recurrent selection (RS) is a viable alternative for breeding of this crop; nevertheless, it is necessary to frequently evaluate the progress achieved. Consequently, the purpose of this work was to assess the genetic progress obtained after two cycles of RS for the traits of popping expansion (PE) and grain yield (GY). Cycles one and two of the UFLA - E and UFLA - R populations, the original population (UFLA) and two controls were assessed. The experiment was conducted at the UFLA experimental farm in a randomized block design with eleven replications; ten agronomic traits, including PE and GY, were assessed. Gains from selection for the traits studied were observed, as well as that the type of kernel had an influence on the response for genetic progress for the PE trait and that the populations assessed exhibited potential for future selection cycles.

Morpho-anatomical characterization of root in recurrent selection cycles for flood tolerance of maize (Zea mays L.)

Changes in root anatomical structures at successive cycles of selection (cycle 1 to cycle 18, alternating) were observed in the study of maize (<i>Zea mays</i> L. cv. Saracura-BRS 4154) capable to survive and produce in temporarily flooded soils; this cultivars was developed by the Maize and Sorghum National Research Center through stratified phenotypic recurrent selection for cultivation wetland soils. Field trial was carried out and flooding of the soil was initiated at the six-leaf stage; the soil was flooded with water (20-cm deep) three times per week. Root sample was collected, fixed, and selected for observation in photon microscope. A gradual increase in the number of aerenchyma, the proportion of vascular cylinder, smaller metaxylem, and phloem and epidermis width, and a decrease in exodermis and cortex were observed in successive selection cycles. Such phenotypic changes impart the flood tolerance ability to this maize cultivar.